The Cataclysm update is now live! Download the patch and jump into the game to finish brand new challenges, new story missions and events. Use the new crystal currency to buy seasonal items in the new store tab. Patchnotes can be found at the bottom.
ChaosprimeZ and GameAndReload made a complete Cataclysm guide video. If you don't mind some spoilers and want to finish all events as soon as possibble you can watch the video below. There is still no release date for the Cataclysm but the test servers are closed and it should arrive soon.